Method for producing calcined coke pellets

Abstract

An improved method for producing calcined coke agglomerates having good stability including adjusting the fluidity of coals or blends of coals to within a range of 1300 DDPM and 3000 DDPM, mixing the coals or blends of coals with char and optionally topped tar in a rotating agglomerating drum and agglomerating the mixture at a temperature between 750° F. and 875° F. (399° C.and 468° C.) for a time to form partially coked green coal agglomerates generally spherical in shape and calcining the partially coked green coal agglomerates at a temperature between 1500° F. and 2000° F. (815° C. and 1093° C). The calcined coke agglomerates are characterized by having a stability of not less than 60%.

I claim: 
     
       1. An improved method for producing calcined coke agglomerates having a stability index of not less than 60 percent from coals and blends of coals comprising: (a) adjusting the fluidity of the coals and blends of coals to between 1300 DDPM and 3000 DDPM,   (b) charging a mix of the coals and blends of coals at a preheated temperature and char heated to a temperature higher than that of the coals and blends of coals into a rotating agglomerating drum,   (c) heating the coals and blends of coals by heat exchange from the char while agglomerating the mix in the rotating drum to form partially coked green coal agglomerates,   
     
     
       (d) discharging the partially coke green coal agglomerates from the rotating agglomerating drum, (e) charging the partially coked green coal agglomerates into a calcining furnace, and   (f) heating the partially coked green coal agglomerates in the furnace for a time at a temperature to produce calcined coke agglomerates.   
     
     
       2. The method of claim 1 wherein the fluidity of the coal is adjusted in step (a) by heating the coal in air at a temperature for a time to partially oxidize the coal. 
     
     
       3. The method of claim 1 wherein the fluidity of the coal is adjusted in step (a) by blending a quantity of at least two coals of different fluidities to form a blend of coals having the desired fluidity. 
     
     
       4. The method of claim 1 wherein an amount of preheated topped tar is charged into the rotating agglomerating drum with the coals and blends of coals and char in step (b). 
     
     
       5. The method of claim 1 wherein the partially coked green coal agglomerates discharged from the agglomerating drum in step (d) are generally spherical in shape and about 50% of the agglomerates have a size of about one inch to three inches in diameter. 
     
     
       6. The method of claim 1 wherein the partially coked green coal agglomerates are heated to within a temperature range of 1500° F. to 2000° F. for about two hours to four hours in step (f). 
     
     
       7. A method for producing calcined coke agglomerates characterized by having a stability index of not less than 60 percent when tested by a modified tumbler test and a size within the range of one inch to three inches in diameter, said calcined coke agglomerates being made from a raw material mix containing coals and blends of coals, char and topped tar, which mix is agglomerated in a rotating agglomerating drum to form spherical-like partially coked green agglomerates at a temperature within the range of 750° F. to 900° F. (399° to 482° C.), the method comprising: (a) adjusting the fluidity of the coals and blends of coals to between 1300 DDPM and 3000 DDPM,   (b) charging the coals and blends of coals preheated to a temperature between 550° F. and 650° F. (288° C. and 347° C.), char preheated to a temperature between 1100° F. and 1200° F. (593° C. and 648° C.), and topped tar preheated to a temperature between 575° F. and 625° F. (305° C. and 330° C.) into said rotating agglomerating drum to form a mix containing between 36 and 39 weight percent coals or blends of coals, 60 and 57 weight percent char and about 2 to 6 weight percent topped tar,   (c) retaining the mix of step (b) in the agglomerating drum for a time at a temperature to form partially coked green coal agglomerates,   (d) discharging the partially coked green coal agglomerates from the rotating agglomerating drum,   (e) charging the partially coked green coal agglomerates into a calciner,   (f) heating the partially coked green coal agglomerates to a temperature between 1500° and 2000° F. (815° to 1093° C.) in the calciner for a time to calcine the green coal agglomerates,   (g) cooling the calcined coke agglomerates, and   (h) discharging the calcined coke agglomerates from the calciner.   
     
     
       8. The process of claim 7 in which the fluidity of the coal in step (a) is adjusted by preheating the coal at a temperature within the range of about 450° to 600° F. (232° to 315° C.) for a time to partially oxidize the coal prior to charging into the rotating drum. 
     
     
       9. The process of claim 7 in which the fluidity of the coal in step (a) is adjusted by blending portions of weakly caking or non-caking coals and a good caking coal. 
     
     
       10. The process of claim 7 in which the partially coked green coal agglomerates are heated within a temperature range between about 1500° F. and 2000° F. for between about two to four hours in step (f).